linux-kernel - Re: [PATCH 2/3] x86/sysfb_efi: Fix valid BAR address range check

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Message-ID: <20160504154344.GA3146@udknight>
Date:	Wed, 4 May 2016 23:43:47 +0800
From:	Wang YanQing <udknight@...il.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Matt Fleming <matt@...eblueprint.co.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H . Peter Anvin" <hpa@...or.com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	David Herrmann <dh.herrmann@...il.com>,
	Peter Jones <pjones@...hat.com>, stable@...r.kernel.org,
	Tomi Valkeinen <tomi.valkeinen@...com>
Subject: Re: [PATCH 2/3] x86/sysfb_efi: Fix valid BAR address range check

On Wed, May 04, 2016 at 08:35:24AM +0200, Ingo Molnar wrote:
> 
> * Matt Fleming <matt@...eblueprint.co.uk> wrote:
> 
> > From: Wang YanQing <udknight@...il.com>
> > 
> > We can't just break out when meet start is equal to zero,
> 
> Hm, wot?
> 
> Thanks,
> 
> 	Ingo

Sorry for my poor English ,and poor commit message, this bring
trouble for more than one maintainer, I guess.

The old code use below comparion as condition to terminate valid 
range check without care whether there are more ranges in later
BARs:
"
        if (start == 0)
            break;
"

I guess original author think (or make a mistake) when we meet a 
address range begin from zero means it is a invalid address range, 
and no valid address ranges in remain BARs.

So I said:
We can't break the loop when meet range whose start address is zero,
without check it and remaining BARs' range.

Thanks.